Fracture cause analysis for right rear suspension bolt of a certain type of machine powertrain

The right rear suspension bolt of a certain machine powertrain was fractured in durability tests. In order to analyze the cause of fracture, the macroscopic fracture morphology analysis, micromorphology analysis, metallographic structure analysis, hardness and composition tests of the bolt were carried out first. The metallographic structure, hardness and composition test results showed that the bolt material met the requirements. The results of fracture morphology analysis show that the failure mode of the faulty bolt is Low-cycle high-stress fatigue fracture. In order to further explore the cause of bolt fracture, We established the finite element model of the powertrain and frame, then extracted the load of the right rear suspension bolt of the machine powertrain. The faulty bolt was checked according to the extracted load. The bolt strength was insufficient to meet the requirements of clamping force, which was the main reason for the failure. Referring to the research in this article, this fault was solved by improving the connection design and increasing the number of bolts.